Pardon me for a minute, I’m about to geek this up.

I’m tired of major media outlets like NBC and ESPN automatically crowning the men’s 100m winner “the world’s fastest man”. The world’s fastest man is actually Michael Johnson with his 19.32s in the 200m.

The current world record for 100m is Asafa Powell’s 9.74s set the other day. The world record for the 200m is Johnson’s race from the Atlanta Olympics. Let’s compare:

distance / time = velocity
100m / 9.74s = 10.27 meters/second
200m / 19.32s = 10.35 meters/second

The 200m time is actually faster. You could argue that because we only have 3 significant figures measuring the 100m time, the most precise velocity we have is actually 10.3 m/s–still not fast enough with rounding. Furthermore, the 200m time would round to 10.4 if it had the same constraints.

If you split Johnson’s 200m race into 2×100’s:
19.32s / 2 = 9.66s

So, the next “world’s fastest man” will either be the first person to run a 200m in 19.31s, or break the 100m world record running 9.65 or better. Other notes worth pointing out: